Pipe line strainers are designed for installation in the water supply connection to automatic sprinkler, water spray deluge, foam-water deluge, or standpipe fire protection systems. The strainers are used in systems where it is necessary or desirable to protect spray nozzles, sprinklers and/or other types of discharge outlets from obstruction by debris that may be present in the water supply. A typical strainer consists of a body that defines a conduit providing water flow from an inlet to an outlet, with a basket screen therebetween to stop debris having dimensions greater than, e.g., about 1/8 inch which may be present in water supply.